2' high at 20' away is a good rule of thumb. And a good starting point. I've used this rule since my first headlight adjustment back in the 80's,
It works very well. If it is too low while driving, then raise the height a little. Just not enough to blind on-coming traffic. Fog lights should be below the headlight beams

High beams are at 2' as well. This is how I adjust headlights. This way just eliminates a step. But, this is the full adjustment procedure::::

From start to finish: on a level surface, pull as close to the wall as u can without hitting the wall, with the lights on, put tape on the wall where the beam of light hits it, horizontally and vertically, will look like a big plus + for both sides, driver and passenger side. Once u have the tape in place, drive/pull the car back 25 feet and see where the headlight beams are, you want them to be 2 inches lower than the horizontal tape and 2 inches to the right of the vertical tape, so you're not blinding on-coming traffic. The light beams will be just below (horizontal tape) and to the right of the vertical tape. Adjust the high beams in the same manner.

If you look at some headlight "lenses" they will have little nipples on them, those nipples are used for adjustment with a special adjustment kit. 1 of those nipples will have the letters and number HB2 or HB4, this is for the high beam adjustment using that special kit. My 01 SS has HB4 on the lenses. A lot of the newer vehicles don't have those nipples anymore.